AltRB

altRB refers to an alternative implementation or family of red-black tree data structures used to provide ordered map and set containers. The term is not tied to a single canonical project, but rather to variants that seek to optimize aspects such as memory layout, cache locality, or integration with specific runtimes.

Design and characteristics

Like classical red-black trees, altRB structures maintain balance through color assignments and a set of invariants that ensure the tree remains approximately balanced. This guarantees worst-case time complexity of O(log n) for insertions, deletions, and lookups. Variants within the altRB family may adapt the node layout, use non-recursive algorithms, or apply memory-conscious representations to improve performance on modern hardware.

Operations and interfaces

AltRB-based containers typically provide standard ordered operations found in maps and sets: insert, erase, find, lower_bound, upper_bound, and iterators for in-order traversal. Some implementations expose additional features such as range queries, bulk insertions, or custom allocators. In certain contexts, altRB variants may offer thread-unsafe defaults with optional synchronization or lock-free techniques, though red-black trees are not inherently concurrent.

Performance considerations and use cases

AltRB implementations aim to optimize for workloads where predictable logarithmic performance and ordered iteration are critical, such as in in-memory indexes, databases, or libraries requiring reliable ordered maps/sets. Variants may emphasize cache-friendly layouts to reduce misses or minimize memory footprint, trading off complexity or portability in some scenarios.

See also

Red-black tree, Self-balancing binary search tree, Ordered map, Ordered set, AVL tree.

References

General discussions of red-black trees and their variants provide foundational context for altRB concepts.